| RFC | Status | Reference | Notes |
|---|---|---|---|
| 527 | Status Unknown | D.L. Covill (22 June 1973). R. Merryman (ed.). ARPAWOCKY. Network Working Group. doi:10.17487/RFC0527. RFC 527. | |
| 562 | Status Unknown | A. McKenzie (28 August 1973). Modifications to the TELNET Specification. Network Working Group. doi:10.17487/RFC0562. RFC 562. | NIC 18638. |
